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A common fold mediates vertebrate defense and bacterial attack
Carlos J Rosado1, Ashley M Buckle, Ruby H P Law
1Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia.
Science (New York, N.Y.)
|August 25, 2007
Summary
The crystal structure of a bacterial membrane attack complex/perforin (MACPF) protein reveals similarities to cholesterol-dependent cytolysins. This suggests MACPF proteins may use a similar mechanism to form pores and disrupt cell membranes for defense.
Area of Science:
- Structural biology
- Immunology
- Microbiology
Background:
- Membrane attack complex/perforin (MACPF) domains are crucial in vertebrate immunity and development.
- Vertebrate MACPF proteins like complement C9 and perforin form pores to lyse bacteria and kill infected cells.
- The functional mechanism of MACPF proteins remains largely unknown.
Purpose of the Study:
- To elucidate the structural basis and potential mechanism of MACPF protein function.
- To investigate the relationship between bacterial and vertebrate MACPF proteins.
Main Methods:
- Determined the crystal structure of the bacterial MACPF protein, Plu-MACPF from Photorhabdus luminescens, to 2.0 angstrom resolution.
Main Results:
- The crystal structure of Plu-MACPF revealed significant structural similarity to pore-forming cholesterol-dependent cytolysins (CDCs) from Gram-positive bacteria.
- This structural homology suggests a conserved pore-formation mechanism.
Conclusions:
- Bacterial MACPF proteins, like Plu-MACPF, share structural folds with CDCs, indicating a potential conserved mechanism for membrane attack.
- Vertebrates may utilize a CDC-like mechanism involving MACPF domains for immune defense against pathogens.
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